src: improve StreamBase read throughput

Improve performance by providing JS with the raw ingridients
for the read data, i.e. an `ArrayBuffer` + offset + length
fields, instead of creating `Buffer` instances in C++ land.

PR-URL: https://github.com/nodejs/node/pull/23797
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

1 files changed, 11 insertions, 1 deletions

diff --git a/src/stream_base.h b/src/stream_base.h
index d8e6df960f..039009e072 100644
--- a/src/stream_base.h
+++ b/src/stream_base.h
@@ -264,7 +264,9 @@ class StreamBase : public StreamResource {
   virtual bool IsIPCPipe();
   virtual int GetFD();
 
-  void CallJSOnreadMethod(ssize_t nread, v8::Local<v8::Object> buf);
+  void CallJSOnreadMethod(ssize_t nread,
+                          v8::Local<v8::ArrayBuffer> ab,
+                          size_t offset = 0);
 
   // This is named `stream_env` to avoid name clashes, because a lot of
   // subclasses are also `BaseObject`s.
@@ -326,12 +328,20 @@ class StreamBase : public StreamResource {
       const v8::FunctionCallbackInfo<v8::Value>& args)>
   static void JSMethod(const v8::FunctionCallbackInfo<v8::Value>& args);
 
+  // Internal, used only in StreamBase methods + env.cc.
+  enum StreamBaseStateFields {
+    kReadBytesOrError,
+    kArrayBufferOffset,
+    kNumStreamBaseStateFields
+  };
+
  private:
   Environment* env_;
   EmitToJSStreamListener default_listener_;
 
   friend class WriteWrap;
   friend class ShutdownWrap;
+  friend class Environment;  // For kNumStreamBaseStateFields.
 };